In axial flow gas turbine engines of the type in which the major axis of the combustor(s) extends outwards from the main body of the engine, e.g., at right angles to the engine's rotational axis, it is necessary to provide ducting to turn the combustion gases from the direction in which they leave the combustor into an axial direction for entry to the turbine. Such hot gas ducting also extends around the engine in the form of a so-called “combustion casing”, to distribute the combustion gases evenly around the annular entry to the turbine. To effect such distribution, the combustion casing is arranged to divide the combustion gases flowing from the combustor into two streams extending circumferentially of the engine. One stream flows anticlockwise around the combustion casing and the other flows clockwise. To prevent the two combustion gas streams from colliding head-on at the bottom of the combustion casing, a barrier known as a duct splitter is provided, since otherwise excessive buffeting and turbulence would enter the turbine. However, the opposing streams subject the splitter to flexing and shaking forces, thereby causing fretting and wear problems in the mountings, as described in more detail later.